In contrast to stainless steel surgical instruments that can be sterilized prior to use by exposing the instrument to super-heated steam under pressure at 121.degree. C., an increasing number of medical instruments are heat-sensitive because they are constructed of plastic, fiberoptics, heat-sensitive cements and electronic components. Exposure of such instruments to heat equal to or greater than 55.degree. C. may often destroy the instrument. Heat-sensitive endoscopes penetrate into the lungs (bronchoscopes), esophagus and stomach (gastroscopes), intestines (colonoscopes and sigmoidoscopes), peritoneal cavity (laparoscopes), joints (arthro-scopes), and many other areas of the body where the endoscopes contact blood and other body fluids. These endoscopes provide valuable minimally-invasive inspection, diagnosis and treatment of the body. During use the endoscopes may be contaminated with such serious and deadly microbes as the HIV virus, hepatitis B and C viruses, mycobacteria (TB), pathogenic bacteria, antibiotic-resistant bacteria and pathogenic fungi, for example. The most powerful highest level of disinfectants and sterilants capable of killing virtually all types of pathogenic microbes are used at ambient (18.degree. C.-24.degree. C.) temperatures to disinfect heat-sensitive instruments between patients.
Existing high-level liquid chemical disinfectants and sterilants have many useful properties, but depending on the chemistry may also have many limitations. The formula of this invention solves long-recognized, but unresolved needs of liquid chemical high-level disinfectants useful at ambient temperatures.
Pepper et al. (U.S. Pat. No. 3,016,328) taught that alkaline glutaraldehyde was significantly more antimicrobial than acidic glutaraldehyde. However, alkaline glutaraldehyde is less stable than acidic glutaraldehyde and loses about 40% of its concentration within 7-14 days when buffered with some alkali metal carbonates, such as sodium bicarbonate. Because of this chemical instability, glutaraldehyde was formulated at 2-3 times the concentration necessary for sterilization. This excessive concentration of glutaraldehyde exacerbates the toxic and irritating vapor properties of glutaraldehyde. The formula of this present invention uses a phosphate chemical buffer to achieve a stable alkaline glutaraldehyde that in turn allows sterilization with 50% to 75% less glutaraldehyde accompanied with less toxicity and irritation. It therefore achieves advantages and results not achieved by the Pepper U.S. Pat. No. 3,016,328.
Many scientists have published on the poor tuberculocidal activity of glutaraldehyde (S. D. Rubbo, et al.; T. Bergan, and A. Lystad; F. Collins). In response to this poor tuberculocidal activity, and in response to the instability of alkaline glutaraldehyde, glutaraldehyde formulations have contained high initial concentrations of glutaraldehyde, and directions for use have specified impractical high temperatures (25.degree. C.) and long exposure times of 45 to 90 min. The formula of this invention includes a phenolic chemical with rapid (10-20 min.) tuberculocidal activity at practical ambient temperatures (18.degree. C.-24.degree. C.), therefore having advantages over the present state of the art.
Boucher (U.S. Pat. No. 3,917,850) disclosed that combinations of glutaraldehyde and phenolics were more antimicrobial than either chemical alone. The addition of phenolic chemicals to glutaraldehyde allows the mixture to be tuberculocidal within 10-20 min. at ambient temperatures and at relatively low concentrations of glutaraldehyde; however, Boucher does not contemplate a concentrated two-part system that can be effective at low temperature.